In the construction of new housing and other types of developments, the road system generally is first marked out and the streets into and through the development are cut and graded. Thereafter, the storm water drainage system for the development is constructed, which typically includes the underground drainage pipes, collection boxes and culverts, and drop inlets that form the manholes or drain openings along the street. The culverts are installed after the street bed has been graded to the elevation, whereupon the drop inlets are then installed and connected to the culverts and to the collection boxes. The drop inlets generally are substantially cylindrical concrete pipes that are installed vertically, with their lower ends connecting to the collection boxes and drainage pipes, and their upper ends being substantially at street level.
Once the grading of the street bed has been completed and the drainage system substantially installed, the drainage system then will be buried and the curbs for the street are graded and poured. Thereafter, throats are provided for the manholes, the throats being poured about the open ends of the drop inlets to form the curb inlets or drains and manholes along the sides of the streets through which storm water drains.
During the construction of roads and drainage systems, until the street has been substantially completed and the curbs and throats of the sewer system have been poured, the drainage pipes and inlets must be kept substantially free of dirt and debris pursuant to state and county building codes. Keeping dirt and debris out of the drainage system is, however, very difficult to accomplish as once the curbs are graded and the roads completed, during grading of the curbs as well as additional grading on site, dirt and debris is pushed to the sides of the street by the motor grader or bulldozer, and thus may pass into the open upper ends of the drop inlets. In addition, rain, runoff and wind also tend to wash or blow dirt and debris into the open ends of the drop inlets, which then collects in the collection boxes and sewer pipes.
If dirt and debris are washed into or otherwise collected within the collection boxes and/or other parts of the drainage system, it becomes necessary to send laborers down into the drop inlets and collection boxes to manually clean out the dirt and/or debris that has been washed or accidentally dropped into the drainage pipes to comply with building code regulations. Such cleaning operations are difficult as the pipes are somewhat cramped, making it difficult to maneuver, and there is also the danger of cave-ins or collapse of the dirt, etc. that has built up around the sides of the drop inlets, creating a significant risk of injury or even death to the laborers below. In addition, there can be as much as a ten to twelve-foot drop from the surface of the road, and the upper end of the drop inlet, to the bottom of the collection box on which the drop inlet is mounted. A fall from such a height can cause severe injuries to persons who might inadvertently fall into the inlet, especially as the open end of the inlet becomes obscured by dirt and other debris. The danger of an exposed, i.e. open, ten to twelve-foot drop inlet is especially great for children who might play around the area and are more likely to be curious and to inadvertently fall in and become trapped within the drainage pipes.
In the past, the open upper ends of the drop inlets generally have been protected with a simple silt fence constructed of a flexible mesh or screen material attached to a series of wooden stakes positioned about the open upper end of the drop inlet. Such an arrangement is illustrated in FIG. 1, which shows in general the known method of enclosing and marking the open end of a drop inlet at construction sites. Such arrangements, however, have not proven satisfactory for preventing dirt and debris from falling into the open end of the drop inlet, and they provide little or no protection against persons inadvertently falling into an open drop inlet, and especially for keeping children out of the inlet.
In fact, as shown in FIG. 2, the known silt fences typically tend to collapse, or be blown down, or washed down over a short period of time. This is due to the fact that the mesh of the silt fence and the stakes holding the silt fence in place are not strong enough to withstand heavy rains and wind, and even less so the force of dirt and debris being pushed against the silt fence by a motor grader or bulldozer as the streets and curbs of the site are graded. Under such weight, as illustrated in FIG. 2, the silt fence generally will collapse, often falling into the open end of the drop inlet itself thus permitting the accumulated dirt and debris being urged or pushed thereagainst to fall into the drop inlet.
Although the simplest solution to this problem would seem to be to completely seal the open end of the drop inlet, this is not feasible in that rain and storm runoff water must be permitted to drain through the storm water drainage system of the development during construction to permit the ground to dry, and to prevent storm water from eroding the work site and carrying soil and debris to adjacent lots or buildings. Also, the construction site must be kept as dry as possible in order to enable the curbs and throats to be poured and the streets to be finished, which cannot otherwise be accomplished if the ground is too wet to support the concrete as it is poured and formed, thus necessitating a good, open drainage system for the site.
Accordingly, it can be seen that a need exists for a device to cover and protect the open upper end of a drop inlet for a storm water drainage system at new construction developments which will prevent silt, dirt and debris from being washed or blown into the inlet, and will also prevent access to the inlet to minimize the risk of accidents due to persons falling or climbing into the open inlet, but which still allows for the free and substantially complete drainage of storm runoff water into the drainage system at the development site.